Convertible top stack having a triple pivot for a pivot link, center rail, and rear rail

ABSTRACT

A convertible top stack linkage is provided that is formed, in part, in a thixotropic magnesium molding process. Many structural parts of the convertible top stack linkage may be thixotropically molded. A pivot link of the top stack linkage is pivotally connected to two bows, for example, the three and four bows of the top stack. A five bow extends between and is attached to right and left pivot links by right and left pressure links, respectively. A pivot link is provided that has a triple pivot connection to a tensioning link, a center rail and a rear rail. A main spring is secured to a pivot pin and connected to a main pivot bracket on the vehicle to provide a counterbalancing force on the balance link that assists in lifting the top stack linkage as the convertible top is retracted and extended.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. application Ser. No. 10/598,382filed Aug. 25, 2006, which claims priority to PCT ApplicationPCT/US2005/006522 filed Feb. 28, 2005, which claims the benefit of U.S.provisional application Ser. No. 60/548,628 filed Feb. 27, 2004.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a convertible top stack having a pivotlink supporting two bows that shares a common pivot point with a centerrail and a rear rail.

2. Background Art

Convertible tops may be provided on vehicles to provide the option ofconverting a vehicle to an open top configuration. Convertible tops maybe extended to cover a passenger compartment and may be retracted toprovide an open passenger compartment. Convertible tops have a soft topcover that is supported by a top stack linkage in an extended position.The convertible top may be folded by the top stack linkage and stored inthe storage compartment or in the portion of the trunk of the vehiclewhen it is in its retracted position.

Convertible tops generally comprise structural elements such as the topstack and a plurality of transversely extending bows that support aflexible top cover made of cloth generally having a canvas-likeappearance. Convertible tops also generally include a backlight, orwindow. Convertible tops are relatively complex structures that requirefabrication and assembly of many component parts. An objective ofconvertible top design is to minimize the number of component partswithout sacrificing appearance or function.

Each pivot point of a convertible top must be carefully assembled frommultiple components that are secured to a pivot pin. When all of thenecessary components are assembled to a pivot pin with bushings andwashers they are permanently secured with a flaring tool, snap ringfastener, or the like.

Number three and four bows of a convertible top normally requireseparate links that support and position these bows relative todifferent parts of the top stack linkage. Each additional link mayincrease part count and manufacturing expense required to produce theconvertible top.

There is a need for a simplified convertible top structure thatminimizes part count and reduces assembly operations necessary to buildthe convertible top.

These problems and needs are addressed by applicant's invention assummarized below.

SUMMARY OF THE INVENTION

According to the present invention, the method of making a top stacklinkage for a convertible top for a vehicle is disclosed in whichmagnesium is molded in a thixotropic molding process to form at least aone bow, including a front rail portion, a plurality of side rails and aplurality of links. The front rail portion, side rails and links areassembled together with a plurality of bows to form the top stacklinkage for the convertible top.

Other aspects of the invention as it relates to the method of making atop stack linkage comprise molding magnesium in a thixotropic moldingprocess to form a plurality of end portions of a plurality oftransversely extending bows. A plurality of central portions of each ofthe bows is provided, for example, by an extrusion process. The two endportions are each assembled to the central portions to form a completebow.

According to another aspect of the method, the molding step may furtherinclude molding a plurality of fasteners bosses, reinforcing ribs andpivot pin retainers on the front rail portion, the plurality of siderails and the plurality of links. The molding step may also includemolding a rear rail and pressure link that connects the rear rail to thetop stack linkage. The side rails made according to the method mayinclude a central rail and a rear rail. The links may include a scissorlink, control link, pivot link and pressure link.

According to another aspect of the invention, a top stack linkage for aconvertible top for a vehicle having a windshield header is provided.The top stack linkage comprises a one bow that is selectively secured tothe windshield header and is integrally molded to include the right andleft front rails. Right and left center rails are pivotally connected tothe right and left front rails, respectively. Right and left rear railsare pivotally connected to the right and left center rails,respectively. Right and left pivot links are pivotally connected to theright and left center rails and the right and left rear rails on rightand left triple pivot pins. Right and left control links are pivotallyconnected to the right and left front rails and to the right and lefttriple pivot pins, respectively. A two bow extends between and isattached to the right and left center rails. A three bow and a four bowextend between and are attached to the right and left pivot links.

According to other aspects of the invention relating to the structure ofthe top stack linkage, the top stack linkage may further comprise a fivebow extending between and attached to the right and left pivot link byright and left pressure links, respectively. The top stack linkage mayalso further comprise right and left cylinders connected between rightand left center rails and the right and left control links. Thecylinders exert a biasing force on the control links to lift the one bowoff of the windshield header when the top stack is initially retracted.

According to another aspect of the present invention, a convertible topfor a vehicle having a passenger compartment is provided that includes atop stack linkage having a right side and a left side. A cover issecured to the top stack linkage and spans between the right and leftside to enclose the passenger compartment of the vehicle. Right and leftsides of the top stack linkage each have a pivot link that is pivotallyconnected to two different bows. Each pivot link is pivotally connectedto one of the sides of the top stack linkage.

According to other aspects of the invention as they relate to theconvertible top, the pivot link may be connected to a tensioning linkthat applies tension to a rear bow. The tensioning link may be connectedto the pivot link at a location that is disposed rearward of thelocation where the pivot link is connected to the right and left topstack linkages. The pivot link may also be connected by a triple pivotto a center rail and a rear rail. The pivot link may also be pivotallyconnected to a control link at a location that is disposed forward ofthe triple pivot. The pivot link may also be pivotally connected to acontrol link. The two different bows may each be secured to the cover atspaced locations.

According to another aspect of the present invention, a convertible topfor a vehicle having a passenger compartment is provided that includes amain spring that assists in lifting the top stack linkage as theconvertible top is retracted and extended. The convertible top includesa top stack linkage that has a right side and a left side. A cover issecured to the top stack linkage and spans between the right side andthe left side to enclose the passenger compartment of the vehicle. Theright and left sides of the top stack linkage each have a main springsecured to a pivot pin that is connected to a main pivot bracket. A rearrail is connected to the main pivot bracket on a lower end and to theother parts of the top stack linkage on its upper end. A balance link issecured to the pivot pin on its lower end and to a center link on itsupper end. The main spring provides counterbalancing force on thebalance link for assisting in lifting the top stack linkage.

According to other aspects of the invention as they relate to theconvertible top, the main spring may have a forked end that engages thebalance link. The right and left sides of the top stack linkage may eachfurther comprise a cylinder connected between the center rail and acontrol link wherein the cylinder exerts a biasing force on the controllink to lift a front portion of the top stack linkage as the convertibletop is retracted.

The above-described aspects of the present invention and other featuresand advantages will be better understood in view of the attacheddrawings and following detailed description of the illustratedembodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation view of a convertible top and top stacklinkage made according to the present invention;

FIG. 2 is a fragmentary, partially exploded perspective view of a topstack linkage made according to the present invention;

FIG. 3 is a perspective view of a portion of a top stack linkage madeaccording to the present invention; and

FIG. 4 is a cross-sectional view taken along the line 4-4 in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Referring to FIG. 1, a convertible top 10 is illustrated including a topstack 12. The convertible top includes a one bow 14 that is adapted tobe secured a windshield header 16. Moving rearwardly from the one bow,the other bows of the top stack 12 are identified as a two bow 18, athree bow 20, a four bow 22, and a five bow 24. The bows support the topcover 26 when the convertible top 10 is in its extended, or passengercompartment covering, position. A headliner 28 extends from the one bow14 to the four bow 22 and is secured to each of the bows except for thefive bow 24.

The one bow is integrally formed with a front rail portion 30. The frontrail portion 30 of the one bow 14 is connected on its rearward end to acenter rail 32 and control link 34.

The two bow 18 is connected to a scissor link 36. An upper cylinder 38is connected to the center rail 32 and scissor link 36 on opposite ends.When it is desired to retract the convertible top 10, the upper cylinder38 retracts causing the scissor link 36 to rotate in a clockwisedirection as shown in FIG. 1. The scissor link 36 lifts the control link34 that in turn lifts the front rail portion 30 and one bow 14 off ofthe windshield header 16. The connection between scissor link 36 and thetwo bow 18 includes a slot 40 that permits a limited degree of lostmotion connection between the scissor link and the two bow 18.

The center rail 32 is connected on its rearward end to a pivot link 42and a rear rail 44 on a triple pivot pin 46. Pivot link 42 is alsoconnected to the control link 34. Pivot link 42 is pivotally connectedto each of the three bow 20 and four bow 22. The rearward end of thepivot link 42 is connected to the pressure link 48. Pressure link 48interconnects the pivot link 42 with the five bow 24. As the pivot link42 is rotated during the retraction cycle, the pressure link 48 liftsthe five bow 24. At the same time, the pivot link 42 moves the three bow20 and four bow 22 rearwardly.

The rear rail 44 is connected on its forward end to the center rail 32and is attached to the five bow at an intermediate point on its lowerportion. The rear rail 44 is also pivoted on its lower end to the mainpivot bracket 52.

A main spring 54 is supported on the main pivot bracket 52. The mainspring 54 is a power spring used to counterbalance the weight of theconvertible top 10 during its extension and retraction cycles. A lowercylinder 56 is also provided as part of the main pivot bracket assembly52. A balance link 58 is connected to the main pivot bracket assembly 22and the main spring 54 on its lower end. The upper end of the balancelink 58 is connected on its upper end to the center rail 32.

As the top is retracted, the rear rail 44 rotates in a clockwisedirection, as viewed in FIG. 1, about the main pivot bracket 52. Thebalance link 58 also rotates in a clockwise direction about the mainpivot bracket 52 thereby causing the center rail 32 to rotate upwardlyand rearwardly in a generally clockwise direction. As the retractioncycle continues, the one bow 14 rotates over the center rail 32 and thethree and four bows rotate rearwardly toward the five bow 24.Ultimately, the retraction cycle is completed with the bows stacked inthe storage compartment located behind the main pivot bracket 52.

Referring to FIG. 2, the control link 34 is shown removed from the pivotpoint that connects the control link 34 to the front rail portion 30 ofthe one bow 14 on its front end. The control link 34 is also shownexploded from its pivot point with the pivot link 42. Pivot link 42 isshown connected to the center rail 32 and rear rail 44 at anintermediate point on the pivot link 42. The rear end of the pivot link42 is shown connected to the pressure link 48. The connection betweenthe main pivot bracket assembly 52, rear rail 44, and balance link 58are also illustrated. The main spring 54 exerts a counterbalancing forceon the balance link 58 throughout the retraction and extension cycles.

Referring to FIG. 3, the connections between balance link 58, mainspring 54, and main pivot bracket 52 may be seen in greater detail. Themain pivot bracket 52 is connected to the rear rail 44 at the lower endof the rear rail 44. The balance link is pivoted on a spring mount pivotpin 60 to which the main spring 54 is also mounted. A forked end 62 ofthe main spring 54 engages the balance link 58 at a point radiallyspaced from pivot pin 60. The main spring 54 exerts a force on thebalance link 58 that assists in lifting the convertible top 10 throughthe center rail 32 and one bow 14.

Referring to FIG. 4, the triple pivot pin 46 is shown in cross section.The triple pivot pin 46 is journaled by the center rail 32 on oppositeends of the pin 46. The pivot link 42 is also assembled to the centerportion of the triple pivot pin 46. The rear rail 44 is secured to thepin 46 between the pivot link 42 and outer ends of the pin 46 where thepin 46 is connected to the center rail 32.

FIG. 4 also illustrates the relationship of the three bow 20 and topcover 26 relative to the center rail 32. The three bow 20 is connectedon pivot pin 64 to the pivot link 42.

Several parts of the top stack 12, and also the handle hardware andlatch mechanisms can be formed advantageously with a Thixomolding®process in which Magnesium is heated to its thixotropic state andinjection molded to form the parts to net size and shape. TheThixomolding® process allows fastener bosses, reinforcing ribs, class Asurfaces and pivot pin retainers to be formed without additionalmachining operations. In particular, the one bow 14 including the frontrail portion 30, center rail 32, scissor link 36, control link 34,scissor link 36, pivot link 42, rear rail 44, pressure link 48, and endportions of the two through four bows 18, 20 and 22 may all befabricated using the Thixomolding® process.

While embodiments of the invention have been illustrated and described,it is not intended that these embodiments illustrate and describe allpossible forms of the invention. Rather, the words used in thespecification are words of description rather than limitation, and it isunderstood that various changes may be made without departing from thespirit and scope of the invention.

1. A top stack linkage for a convertible top for a vehicle having awindshield header, the top stack linkage comprising: a one bow that isselectively secured to the windshield header, the one bow beingintegrally molded to include right and left front rails; right and leftcenter rails pivotally connected to the right and left front rails,respectively; right and left rear rails pivotally connected to the rightand left center rails, respectively; right and left pivot linkspivotally connected to the right and left center rails and the right andleft rear rails on right and left triple pivot pins; right and leftcontrol links pivotally connected to the right and left front rails andto the right and left triple pivot pins, respectively; a two bow extendsbetween and is attached to the right and left center rails, and a threebow and a four bow extends between and are attached to the right andleft pivot links.
 2. The top stack linkage of claim 1 further comprisinga five bow extending between and attached to the right and left pivotlinks by right and left pressure links, respectively.
 3. The top stacklinkage of claim 1 further comprising right and left cylinders connectedbetween the right and left center rails and the right and left controllinks, wherein the cylinders exert a biasing force on the control linksto lift the one bow off of the windshield header when the top stack isinitially retracted.